Non-compressible sites of torso vascular injury remain one of the leading causes of potentially preventable death in both active duty troops during wartime conflict and in civilian trauma centers. An example of this type of torso vascular injury is a gunshot wound to the abdomen with a central site of bleeding and a patient in shock. Unlike an extremity injury, wherein a tourniquet could be used for vascular control or direct pressure could be held at select arterial pressure points, vascular injuries to the torso require surgical exposure followed by the often difficult application of vascular clamps for hemorrhage control. In a patient group presenting in shock, the time it takes to achieve such exposure and control may mean the difference between life and death. Specifically, the end stages of shock from hemorrhage or cardiac or neurologic causes are accompanied by critically low blood pressure and circulation to the brain and heart, which eventually lead to neurological death, cardiac arrest, or both.
Currently accepted methods of controlling hemorrhage in other areas of the body are not effective in treating torso hemorrhage. For example, while tourniquets have been developed and used successfully to manage bleeding from injured limbs, they are not successful in controlling torso bleeding. Manual pressure with and without new topical hemostatic agents and bandages has been taught for extremity and head and neck wounds, but is not successful for torso vascular injury. However, without similar expeditious maneuvers to address uncontrolled hemorrhage in the torso, this pattern of bleeding remains the leading cause of potentially preventable death on the modern battlefield and occurs frequently in civilian trauma centers.
Moreover, one currently acceptable method of managing non-compressible torso hemorrhage, i.e., open resuscitative thoracotomy with clamping of the thoracic aorta, has major limitations. For example, the performance of an emergency or resuscitative thoracotomy is maximally invasive as it involves a large opening of the left chest with retraction of the left lung and other vital structures to expose the thoracic aorta for clamping. As such, resuscitative thoracotomy requires specialized surgical instruments and lighting, and can only be performed by a select group of highly trained medical professionals. Patients undergoing this surgical maneuver require general anesthesia with endotracheal tube insertion and mechanical ventilation. If a thoracotomy with aortic cross-clamp placement is successful, the patient will have the added morbidity of an additional, large, cavitary wound from which to recover.
Thoracotomies are considered one of the most difficult surgical incisions to manage post-operatively, as they are extremely painful and frequently lead to lung complications. Chest wall pain and manipulation of the left lung from the procedure can prevent the patient from breathing effectively, and may lead to pneumonia. Notwithstanding these drawbacks, resuscitative thoracotomy is the only known and widely accepted method to control bleeding and support central blood pressure (i.e., perfusion to the heart and brain) in this setting. Acknowledged as an effort of last resort, this complex surgical maneuver is maintained as standard, despite the absence of significant tangible advances in the technique for the last four decades. Aside from refinements in determining which patients are best suited for this surgery, versus those in whom this is futile, the technique of occluding the thoracic aorta through an open incision, retracting the lung and clamping the aorta remains substantially the same in 2010 as it was in 1970. Further, the supporting literature demonstrates that survival associated with this surgery is less than 5%, considering all patients in whom it is performed.
Despite these substantial drawbacks, the fact that the surgical maneuver continues to be pursued, although old, suggests that the purpose behind the surgical maneuver, i.e., resuscitative thoracic aortic occlusion, has physiologic merit. The advantage of occluding the thoracic aorta in this setting is further substantiated by documented attempts at using rudimentary balloons within the thoracic aorta to accomplish this same result, i.e., occluding distal flow to the lower half of the body where the bleeding is occurring, and to support perfusion to the brain and myocardium. More specifically, use of a compliant balloon as a potentially effective treatment to emergency thoracotomy has been quietly explored for decades. The earliest reports describing this exploration in animal models were in the 1950s.
However, the technique of balloon occlusion in the thoracic aorta of young trauma victims was, and continues to be, inadequate because of deficient balloon design and the requirement for fluoroscopy in order to deploy any such devices. For example, currently marketed compliant occlusion balloons are available for use in ruptured aortic aneurysms, which by necessity has resulted in their extremely large diameter (up to 42 mm). Two examples of such aortic balloons are the Reliant (Medtronic Vascular), with a recommended delivery sheath of 12 French, and Coda (Cook Medical), with a recommended delivery sheath of 14 French. Each of these balloon systems require specialized and often scarce radiographic imaging (i.e. x-ray or fluoroscopy) to place and inflate them in the correct position in the thoracic aorta.
These large balloons require large diameter sheaths (12-14 French) which must be placed inside of the femoral and external iliac artery, and have not been designed for use specifically in the setting of non-compressible torso hemorrhage. In other words, the occlusion balloons have a large diameter design made for use in elderly individuals affected by aneurysm disease, and not for the normal aorta of young adult civilian trauma victims or injured military troops. Also, the delivery shafts of currently available balloons are too flexible to remain in position without a supporting sheath. As such, available occlusion balloons required very large and extended length sheaths in order to be delivered to and maintained or fixed at the desired position in the thoracic aorta.
Further, the balloons mentioned as examples above do not have a mechanism for safeguarding from over-inflation, which is why each must be inflated while being directly visualized using x-ray or fluoroscopy to prevent aortic rupture. For example, U.S. Pat. No. 6,719,720 discloses a two-balloon catheter system having a balloon-within-a-balloon that is designed to limit high arterial pressures to a defined location at the central site of ballooning. However, there is nothing that prevents over-pressurization of the internal aortic balloon.
The conventional technique of balloon occlusion is also limited by reliance upon x-ray or fluoroscopy to deliver and inflate the balloon within the correct position. For example, each of the balloons mentioned above can occlude an aorta, but each needs to be inflated under fluoroscopy to prevent aortic rupture. U.S. Pat. No. 5,738,652 discloses a catheter for use with inducing cardioplegic arrest in a patient that includes at its distal end a balloon “configured to occlude the coronary sinus of a patient's heart, and has a length and flexibility which allow the distal end to be positioned in the coronary sinus with the proximal end extending transluminally to a peripheral vein . . . and out of the body through a puncture therein.” See U.S. Pat. No. 5,738,652 (Abstract). However, fluoroscopy is required to use this balloon catheter for such procedures. See U.S. Pat. No. 5,738,652, col. 4, lines 10-16 (“a body of clear fluid can be maintained in the aortic region upstream from the expanded distal end of the aortic catheter to facilitate imaging, e.g., angioscopic observation, of the cardiac procedure”) and col. 8, lines 25-27 (“Shaft 122 is preferably radiopaque to permit fluoroscopic observation thereof to facilitate positioning.”). Thus, the requirement of x-ray or fluoroscopy to use currently available balloon occlusion systems restricts performance of this procedure to fixed operating rooms with C-arm capabilities or fixed imaging suites, both of which are typically not available in trauma or emergency settings.
In addition to balloon occlusion, various other endovascular procedures are predicted on, or tied to, the use of real time fluoroscopy to visualize devices within the torso vessels. Although fluoroscopy affords visualization of endovascular procedures, the need for this modality carries a significant burden. Specifically, fluoroscopic imaging is costly and its requirement severely limits where catheter-based endovascular procedures can be performed and who can perform them. The requirement for fluoroscopy means that valuable and potentially lifesaving interventions can only be performed by a select number of trained providers in adequately equipped facilities often hours from a point of injury. Even routine or elective endovascular procedures may be delayed as they compete in a resource limited environment among a pool of procedures to be completed using fluoroscopic equipment in the intensive care unit, operating room or endovascular imaging suite. In addition, in emergency, intensive care or surgical environments, fluoroscopy is often not readily available or the environments in which the patients are positioned, e.g., an intensive care unit (ICU) bed or operating room (OR) table, are not specifically made for imaging, thereby impeding the use of fluoroscopy.
U.S. Pat. No. 4,713,888 to Broselow discloses a pediatric emergency tape that informs a physician of equipment lengths and sizes to perform emergency resuscitation on a child. The tape also provides references at each weight zone on the tape corresponding to pre-calculated medication dosages. However, there is no similar device for adult torso vascular anatomy, i.e. morphometry, which will facilitate or guide endovascular procedures of the torso.
In sum, existing and related technologies differ from the system and method of the present disclosure in function and form. Regarding function, current technologies were designed and approved for use in the temporary occlusion of large blood vessels, or to expand vascular prostheses (e.g., endovascular stent grafts in the elderly). In form, however, current related technologies were designed and approved for use with fluoroscopy, for both device positioning and device inflation. In contrast, the system and method of the present disclosure are designed specifically for use in a young adult population exposed to non-compressible torso hemorrhage from trauma or other forms of cardiogenic or neurogenic shock, who have normal aortic diameters, and importantly, without dependence on fluoroscopy.